6 Volt to 12 Volt Conversion FAQs

Here are some of the most frequent questions we get about 12 volt conversions here at Steiner Tractor Parts. If you’re thinking about making the switch, here are some good tips:

Why convert from a 6 volt to a 12 volt system? There are a few advantages to a 12 volt system – tractors that operate on 12 volts start faster and have brighter headlights. A 12 volt battery lasts longer than a 6 volt, and you can jump-start a 12 volt tractor with an ordinary vehicle. Switching to an alternator eliminates the need for a generator and voltage regulator, giving you a more reliable charging system.

Is it a difficult project? Making the conversion isn’t incredibly difficult, but it’s not a project for a beginner, either. I would rate it as a moderate difficulty. In addition to basic mechanical skills, you also need to know the basics of electrical wiring. If you have the tools and knowledge to change a light fixture in your home (including stripping wires and using stake-ons properly), you’re ready.

What parts do I need? A standard conversion will require an alternator, alternator bracket, battery, coil, wiring harness, and amp gauge. Replace the existing generator and voltage regulator with the alternator, and swap out the old battery, coil, wiring harness, and amp gauge with the new.

When doing a 12 volt conversion, do I need a 12 volt starter? In my opinion, no. While some starter shops will sell you a “specially wound 12 volt starter” in my opinion there’s no reason or a big enough difference to warrant this expense. Your original (or replacement) 6 volt starter will function well on a 12 volt system.

Do I have to change the wiring? Yes. Your old wiring will be set up for a field, an armature, voltage regulator, etc. Using these existing wires could be a fire hazard. Replace your wiring harness with a new one specific to your tractor to have a cleaner look and safer operation.

Do I need to change the coil? Yes. The 12 volt coil upgrade is very important. I’ve seen some people try to place a resistor in front of their 6 volt coil–not a good idea. The resistor won’t suffice.

When I do the 12 volt conversion, do I keep the voltage regulator? No. The voltage regulator needs to be removed when putting an alternator on.

Can I just install an 8 volt battery on my 6 volt system? Yes you can. No changes are required. Many people choose this option.

Do you have videos available? Yes I do! If you are converting a Farmall tractor, you’re in luck! Here’s a link to a video I made on a Farmall tractor. Even though the demonstration model is a Farmall, though, the basic techniques are similar across all makes and models. If you’re looking for help on a different tractor, give a shout in the comments! I’m always happy to hear video ideas.

Your tutorial is well thought out,and spot on if but for one piece of advice…when doing the conversion,your new 12 volt system will indeed engage the 6 volt starter,however when you start to break the nose cone on the starter,and it will break….due to the extra volts sent to the starter.You have several options: new 12 volt starter,keep replacement nose cones on hand,or what I did was braise the cone back together,and made a brass bushing with an 1/8th inch flange for the pinion gear to hit…this bushing acts as a shock absorber…It was easy enough,but I have a machine shop,so it was 15 mins…but one could find a shop to make it…Ever since I made that bushing I’ve had no issues,5 yrss ago…..So,yes one does need to address the starter.

Im getting ready to try and convert my JD 40 C to 12 volts for the 2nd time. First time around I cooked the alternator off of a 1976 GMC 350. I changed the coil to the NAPA one recommended switched to 12 volt battery negative ground wired the 10 ga wire from Batt lead on 10si single wire alternator to amp meter, this time Im using a volt meter, but Im not clear on the ignition wires to the coil. Does the ignition wire hook to the negative side of the coil? and on the 10SI alternator there is a plug along side of the alternator number 1 and 2 it looks as though 1 is hooked to Batt on Alternator with 10 ga wire and 2 goes to coil BUT this is a hook up using a ballast resister. Is this hook up the same without the resister?

My Ford 641 had a 6vdc starter with positive ground. When I converted from 6 to 12 vdc a decade ago it also resulted in converting the polarity, so why doesn’t the starter turn backwards if the polarity is reversed? My new 12VDC system has worked flawlessly.

Harold we carry the I&T Shop Service Manual which tells you how to take a tractor apart, how to fix it and how to put it back together again. I added the link below for your brand and model. Good luck on your project.

I,m converting my allis chalmers tractor model B 6 volts to 12 volts. Is there a conversion wiring diagram for this model tractor? Is there one on line? If there is how do I get to it to copy the diagram

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